In recent years, trials have been conducted of introducing genetic analysis into medical settings and the like. These trials have involved testing and analysis of nucleic acids extracted from biological samples. Biological samples refer to various bodily fluids such as blood, plasma, serum, semen and lymphatic fluid, various tissues such as skin, hair and muscle tissue, and various excreted substances such as feces and urine obtained from a target living organism (or the corpse of a living organism), as well as other samples derived from the above samples. Testing of these biological samples offers the possibility of rapid detection of diseases and their pathogenic risk, as well as early detection of infectious diseases and malignant tumors.
Extraction of a nucleic acid from a biological sample is an important process in the fields of genetic engineering and clinical testing. For example, in those cases where a blood or tissue sample is collected from a human body and subjected to clinical testing, only the nucleic acid must be extracted from the biological sample such as the blood sample and then purified. In order to separate the protein and the nucleic acid from the other components, the biological sample is first subjected to a physical or chemical dissolution treatment, and an extraction operation is then used to separate the protein and fats from the nucleic acid, thereby extricating the nucleic acid. During this operation, the process of separating and purifying the protein and the nucleic acid is prone to sample contamination. Organic solvents are widely used in standard extraction methods, but suffer from a number of problems, including toxicity of the solvent itself, the time and effort associated with treating discards, the time and effort associated with centrifugal separation operations, and the possibility of contamination of the sample or infection from the sample.
The BOOM method is one known method for extracting and collecting a nucleic acid. The BOOM method is a nucleic acid extraction technique that combines a chaotropic agent and a solid-phase silica or the like, and utilizes adsorption of the nucleic acid on the silica surface in the presence of chaotropic ions.
In conventional methods, the disruption and extricating step, and the extraction and separation step are performed separately, and because the nucleic acid separation and extraction cannot be performed as part of the pretreatment, the possibilities of infection from the sample and contamination of the sample always exist between the two steps. Moreover, because these operations require human involvement, they tend to be inefficient and complex, and there is a possibility that operators may become infected with pathogens.
One example of an apparatus that uses a solid-phase extraction filter is the nucleic acid extraction apparatus disclosed in Patent Document 1. In Patent Document 1, an integrated column having a plurality of columns arranged in a two-dimensional manner is used to enable a plurality of samples to be treated simultaneously. A vacuum chamber is formed by installing this integrated column (extraction filter cartridge) in an airtight manner at an upper opening of a vacuum chamber, enabling a solid-phase extraction to be performed using the so-called suction method. In those cases where a nucleic acid is to be extracted, the series of steps of adsorbing the nucleic acid to a carrier, washing the carrier, and then desorbing and collecting the nucleic acid from the carrier must be performed.
Further, a technique for independently attaching containers (wells) containing the various reagents used for extracting the nucleic acid, a collection container and a waste liquid container to an apparatus has also been proposed (see Patent Document 2). The nucleic acid extraction apparatus and cartridge disclosed in Patent Document 2 enable treatment to be performed without complex reagent dispensing operations, simply by adding the sample to the apparatus, and is therefore ideal for treating large amounts of a plurality of samples.
However, with the techniques disclosed in the above Patent Documents, considerable time and effort is required in preparing the extraction filter cartridges, collection tubes and waste liquid tubes and the like, and even installing these items on the apparatus requires a significant amount of time. Moreover, in these apparatus, there is possibility of contamination of the surroundings before and after operation of the apparatus. In other words, in the nucleic acid extraction process, a plurality of items such as the integrated column or the various containers and the like must be installed on the apparatus and then removed following use, and therefore there are significant possibilities of splashing of the waste liquid due to vibrations or the like, or foam formation depending on the nature of the solutions, resulting in contamination of the extracted sample. Furthermore, during the disposal process, there is a danger that overturning or deviation of the waste liquid tube installed in the apparatus may cause contamination.